Polarization scrambler using a retardance element

ABSTRACT

A polarization scrambler using a retardance element (RE) is disclosed. The polarization scrambler may include an optical fiber input to transmit an optical signal, and a beam expander to receive and expand the optical signal to create an expanded optical signal. The polarization scrambler may include a retardance element (RE) to cause a polarization scrambling effect on the expanded optical signal and to create a scrambled expanded optical signal. The polarization scrambler may include a beam reducer to receive and reduce the scrambled expanded optical signal to create a scrambled optical signal. The polarization to scrambler may include an optical fiber output to receive scrambled optical signal. The optical fiber output may transmit the scrambled optical signal to one or more downstream optical components.

PRIORITY

This patent application is a Continuation of commonly assigned andco-pending U.S. patent application Ser. No. 16/436,481, filed Jun. 10,2019, the disclosure of which is hereby incorporated by reference in itsentirety.

TECHNICAL FIELD

This patent application is directed to optical measurements intelecommunication networks, and more specifically, to a polarizationscrambler using a retardance element for mitigating polarizationdependent loss (PDL) and other polarization-dependent and relatedeffects.

BACKGROUND

Polarization-dependent effects often have undesirable effects infiber-optic systems. These adverse effects may includepolarization-dependent loss (PDL) in various optical components anddevices. Polarization may be uncontrolled and allowed to passively driftin a network, or it may be controlled deliberately in certain cases,say, for test and measurement. When controlled, it is generallycontrolled using controllers or scramblers.

Existing polarization controllers and scramblers can be expensive tomanufacture, configure, and operate, and usually offer only limited orminimum range of control. These challenges are exacerbated inhigh-speed, in-fiber, defeatable polarization scramblers, wherepolarization-dependent effects can become quite rampant and difficult tomitigate. As a result, a low-cost and effective solution for mitigatingpolarization-dependent and related effects may be needed to overcome theshortcomings of traditional approaches.

BRIEF DESCRIPTION OF DRAWINGS

Features of the present disclosure are illustrated by way of example andnot limited in the following Figure(s), in which like numerals indicatelike elements, in which:

FIG. 1 illustrates a polarization scrambler using a retardance element(RE), according to an example;

FIG. 2A illustrates a patterned retardance element (PRE) with arandomized pattern, according to an example;

FIG. 2B illustrates graphs of light orientation before passing through apatterned retardance element (PRE) and light orientation after passingthrough a patterned retardance element (PRE), according to an example;

FIG. 3 illustrates a planar view of a polarization scrambler using apatterned retardance element (PRE) in a single fiber configuration,according to an example;

FIG. 4 illustrates a planar view of a polarization scrambler using apatterned retardance element (PRE) in a linear fiber arrayconfiguration, according to an example;

FIG. 5 illustrates a planar view of a polarization scrambler using apatterned retardance element (PRE) in a 5×5 fiber array configuration,according to an example; and

FIG. 6 illustrates a flow chart of a method for using a polarizationscrambler with a retardance element (RE), according to an example.

DETAILED DESCRIPTION

For simplicity and illustrative purposes, the present disclosure isdescribed by referring mainly to examples and embodiments thereof. Inthe following description, numerous specific details are set forth inorder to provide a thorough understanding of the present disclosure. Itwill be readily apparent, however, that the present disclosure may bepracticed without limitation to these specific details. In otherinstances, some methods and structures readily understood by one ofordinary skill in the art have not been described in detail so as not tounnecessarily obscure the present disclosure. As used herein, the terms“a” and “an” are intended to denote at least one of a particularelement, the term “includes” means includes but not limited to, the term“including” means including but not limited to, and the term “based on”means based at least in part on.

As described above, polarization-dependent effects often haveundesirable effects in fiber-optic systems. These adverse effects mayinclude polarization-dependent loss (PDL) in various optical componentsand devices. These effects may arise, for example, in systems thatvariously measure a quantities maximum polarization-dependent variation,or alternatively, a quantities average value over all polarizationstates.

Polarization is a fundamental property of light and describes vibrationsof a transverse optical wave. In classical physics, light is anelectromagnetic wave. Polarization is defined in terms of pattern tracedout in the transverse plane by the tip of an electric field vector as afunction of time.

For unpolarized light the electric field vector, may fluctuate randomlyin the transverse plane, along the direction of light beam propagation.Therefore, on average, no direction may be especially favored. The rateof the fluctuation may be so fast that a detector cannot discern stateof polarization (SOP) at any instant of time. In such a state, the lightmay be effectively considered unpolarized. A light beam may generally beconsidered to consist of partially polarized or fully polarized light.Degree of polarization (DOP) is typically used to describe how much inthe total light intensity is polarized. For totally polarized light, DOPmay be one. On the other hand, for completely unpolarized light, DOP maybe zero.

The polarization of light beams may play an important factor inhigh-speed optical communication network system design. Output lightfrom most high-performance lasers used in long-haul opticalcommunication systems may come from highly polarized light sources, andthese components themselves may have polarization sensitive responses.As bit rate increases, fiber optic communication systems may becomeincreasingly sensitive to polarization related impairments, which areusually sought to be minimized. Such impairments may includepolarization mode dispersion (PMD) in optical fibers, polarizationdependent loss (PDL) in passive optical components, polarizationdependent modulation (PDM) in electro-optic modulators, polarizationdependent gain (PDG) in optical amplifiers, polarization dependentcenter wavelength (PDVV) in wavelength-division multiplexing (WDM)filters, polarization dependent response (PDR) in receivers,polarization dependent sensitivity (PDS) in sensors and coherentcommunication systems, polarization dependent coupling (PDC) in taps,combiners, multicore fibers, etc., and other adverse or related effects.

Polarization is generally manipulated using controllers or scramblers. Apolarization controller may be used when a fixed polarization state isdesired. A polarization scrambler, on the other hand, may be used whenone needs to measure the average performance across all polarizations.In particular, temporal scrambling may be achieved by inducing highfrequency SOP (state of polarization) changes. In other words, apolarization scrambler may employ a process of varying the polarizationof light so that an average polarization over time is randomized.

Polarization scrambling, in particular, may be used to mitigatepolarization-related impairments. A polarization scrambler may“scramble” the polarization of light if the SOP of totally (orpartially) polarized light is made to vary randomly at a relatively lowrate. At any instant of time, the SOP may be well defined and the DOPmay be close to one (1). However, on a time average, the DOP may beclose to zero (0). Therefore, the DOP of a scrambled light may depend onthe average time or the detection bandwidth of a detector.

Existing polarization scramblers may be based on several technologies.Among the more popular polarization scramblers are fiber-basedscramblers (e.g., resonant fiber-coil- and fiber-squeezer-based systems)and electro-optic based scramblers (e.g., LiNbO3). Each of thesepolarization scramblers may actively change the SOP using a polarizationmodulation method. Fiber-based scramblers, for example, may be based onactuating a piezoelectric stack or cylinder with fiber-windings tocreate time-varying birefringence. Electro-optic scramblers may be basedon lithium niobate (LiNbO₃) to create time-varying polarizationscrambling and emulation. Performance of a polarization scrambler maygenerally be measured by the degree of polarization of the scrambledlight over a certain period of time and the uniformity of the SOPPoincare sphere coverage. In practice, the wavelength sensitivity andtemperature sensitivity of the performance of the scrambler may also beimportant for real world applications.

A technical problem with these existing polarization scramblers is thatthey can be rather expensive to manufacture, configure, or operate, andsuch scramblers typically offer only limited or minimum range of controland may be limited to narrow wavelength ranges. These challenges areexacerbated in high-speed, in-fiber, defeatable polarization scramblers,where polarization-dependent effects can become quite rampant anddifficult to mitigate. It should be appreciated that “defeatabie,” asused herein, may refer to an ability or an effect that can be activatedor deactivated.

Accordingly, a polarization scrambler that utilizes a retardance element(RE) and an efficient minimalist design may help mitigatepolarization-dependent and other related effects in a low-loss,cost-effective way.

FIG. 1 illustrates a polarization scrambler 100 using a retardanceelement (RE), according to an example. As shown, the polarizationscrambler 100 may be an in-fiber polarization scrambler. In someexamples, the polarization scrambler 100 may include an optical fiberinput 101 a that carries an optical signal 102 a. The optical fiberinput 101 a may be connected to a beam expander 103 a. The opticalsignal 102 a that enters the beam expander 103 a from the optical fiberinput 101 a may be expanded to become an expanded optical signal 104 a.The expanded optical signal 104 a may have a wider, largercross-sectional area relative to the optical signal 102 a. The expandedoptical signal 104 a may travel through a retardance element (RE) 105,which may then “scramble” the expanded optical signal 104 a to become ascrambled expanded optical signal 104 b. The scrambled expanded opticalsignal 104 b may then be received by a beam reducer 103 b, which may besimilar to the beam expander 103 a but operated in reverse. The beanreducer 103 b may shrink the scrambled expanded optical signal 104 b tobecome a scrambled optical signal 102 b. The scrambled optical signal102 b may then pass along the optical fiber output 101 b to one or morevarious downstream components or elements (not shown).

The optical fiber input 101 a and/or optical fiber output 101 b may be asingle mode (SM) optical fiber of varying length or thickness. In someexamples, the optical fiber input 101 a and/or optical fiber output 101b may be a single-mode (SM) optical fiber having a 9 μm core. In thisscenario, the optical signal 102 a may be expanded by the beam expander103 a to be in a range of several hundred square microns (μ²) to tens ofsquare millimeters (mm²). It should be appreciated that this range maybe larger or smaller, depending on the application or use case of thepolarization scrambler 100. In some examples, the optical fiber input101 a and/or optical fiber output 101 b may also be a polarizationmaintaining (PM) optical fiber of varying length or thickness. In thisway, there may be additional benefits of allowing the polarizationscrambler 100 to be optimized for a defined input SOP, if desired.

The beam expander 103 a may include any type of collimator or lenssystem. In some examples, the beam expander 103 a may be agradient-index (GRIN) lens. In some examples, the beam expander 103 amay include any variety of bulk-lenses. It should be appreciated thatthe beam expander 103 a not only expands light, but may causes rays ofthe expanded optical signal 104 a to be parallel with each other. Itshould be appreciated that the beam reducer 103 b may be a symmetric (ornear symmetric) version or identical (or near identical) version of thebeam expander 103 a, but used in reverse, to contract or reduce expandedlight. In fact, each of the beam expander 103 a and the beam reducer 103b may bidirectional, and therefore, these components may be usedinterchangeably.

As described herein, the RE 105 may include properties that cause theexpanded optical signal 104 a to be “scrambled,” or to incur proratedspatially-dependent birefringence. In other words, the RE 105 mayinclude properties that treat different parts of the expanded opticalsignal 104 a in different ways to cause a net polarization scramblingeffect, as shown in the scrambled expanded optical signal 104 b of FIG.1 .

The RE 105 may include any number of materials, contours, or shapes tocause the prorated spatially-dependent birefringence on the expandedoptical signal 104 a. For instance, in some examples, the RE 105 mayinclude a liquid crystal material, such as a birefringent organic liquidcrystal polymer (LCP). In some examples, the RE 105 may include aform-birefringent inorganic thin-film. In some examples, a phasecontrolled surface treatment or other similar treatment may also beused. Other various materials, elements, or treatments may also beprovided.

In some examples, the RE 105 may be a patterned retardance element (PRE)that may include any number of different patterns or designs. FIG. 2Aillustrates a patterned retardance element (PRE) with a randomizedpattern 200A, according to an example. This randomized pattern 200A mayeffectively divide the expanded optical signal 104 a in a plurality ofsmaller parts and allow the light passing through the PRE, in each ofthese smaller parts, to be treated in a different way. In effect, therandomized pattern 200A of the PRE 105 may cause each of these smallerparts of the expanded optical signal 104 a to encounter differentamounts of birefringence, which causes a net polarization scramblingeffect, or differing SOP in and across the scrambled expanded opticalsignal 104 b. It should be appreciated that the randomized pattern 200Amay include any pattern beyond what is shown. For example, therandomized pattern 200A may be a pixelated pattern, a radial pattern, awave or zigzag pattern, a line or linear pattern, a checkered pattern, atextured pattern, a scaled pattern, a gradient pattern, or any otherpattern may create a birefringent effect.

FIG. 2B illustrates graphs of light orientation before passing through apatterned retardance element (PRE) 200B1 and light orientation afterpassing through a patterned retardance element (PRE) 200B2, according toan example. The graph 200B1 depicts of light in a fast-axis orientationbefore passing through the patterned retardance element (PRE) 105. Thegraph 200B2 depicts of light in an output polarization orientation afterpassing through the patterned retardance element (PRE) 105. Here, theoutput SOP may be shown for a particular retarder pattern.

FIG. 3 illustrates a planar view of a polarization scrambler using apatterned retardance element (PRE) in a single fiber configuration 300,according to an example. As shown, the polarization scrambler in asingle fiber configuration 300 may include an optical fiber input 301 a,a beam expander element 303 a, a PRE 305 with a mobile arm 306, a beamreducer 303 b, and an optical fiber output 301 b. Many of thesecomponents are similar to those described with respect to FIG. 1 .

It should be appreciated that the mobile arm 306 may be controlled, viaa motor or other similar actuation element (not shown), so the PRE 305can be moved in any direction along an x-, y-, or z-plane. In someexamples, the mobile arm 306 may vibrate or oscillate the PRE 305 toenhance or improve the scrambling function. In some examples, the mobilearm 306 may move the PRE 305 in-and-out of the optical path. Othervarious movements and configurations may also be provided.

In some examples, the beam expander 303 a and/or beam reducer 303 b maybe coated with a birefringent or retardance element, similar to that ofthe PRE 305 in FIG. 3 . Coating the beam expander 303 a and/or beamreducer 303 b with a birefringent or retardance element may eliminate(or reduce the importance of) a separate and distinct PRE. In somecases, this may reduce cost and create a more efficient, space-savingdesign for the polarization scrambler.

FIG. 4 illustrates a planar view of a polarization scrambler using apatterned retardance element (PRE) in a linear fiber array configuration400, according to an example. The polarization scrambler in the linearfiber array configuration 400 is similar in design and function to thepolarization scrambler 100 and 300 of FIGS. 1 and 3 , respectively.However, the polarization scrambler in the linear fiber arrayconfiguration 400 may include a linear array of optical fiber inputs 401a, a beam expander array element 403 a, a PRE 405 with a mobile arm 406,a beam reducer array element 403 b, and a linear array of optical fiberoutputs 401 b. Although the linear array of optical fiber inputs andoutputs 401 a and 401 b are depicted an array of five (5) opticalfibers, it should be appreciated that any number of optical fibers maybe provided in the linear fiber array configuration 400. While the beamexpander 403 a and the beam reducer 403 b is depicted as a singleelement, it should also be appreciated that the beam expander 403 a andthe beam reducer 403 b may include any number of individual and separateelements.

FIG. 5 illustrates a planar view of a polarization scrambler using apatterned retardance element (PRE) in a 5×5 fiber array configuration500, according to an example. The polarization scrambler in the 5×5fiber array configuration 500 is similar in design and function to thepolarization scrambler 400 of FIG. 4 . However, the polarizationscrambler in the 5×5 fiber array configuration 500 may include a 5×5array of optical fiber inputs 501 a, a beam expander array element 503a, a PRE 505 with a mobile arm 506, a beam reducer array element 503 b,and a linear array of optical fiber outputs 501 b. Although the lineararray of optical fiber inputs and outputs 501 a and 501 b are depictedan array of 5×5 optical fibers, the configuration may be an N×X fiberarray configuration, where N and X may each represent an integer (sameor different). Like FIG. 4 , it should also be appreciated that the beamexpander 503 a and the beam reducer 503 b may include any number ofindividual and separate elements.

While examples described herein are directed to configurations as shown,it should be appreciated that any of the components described herein maybe altered, changed, replaced, or modified, in size, shape, and numbers,or material, depending on application or use case, and adjusted fordesired or optimal polarization scrambling results. For example, theRE/PRE as described herein may also include textured surface, such as anano-structured surface, that have shape factors to producebirefringence. In some examples, the RE/PRE may include aspatial-light-modulation (SLM) material. The SLM-based RE/PRE mayinclude a pixel array with gray-scaled birefringence tuningcapabilities. In some examples, the RE/PRE may be made of apolymer-based material that has domains or regions thereof with varyingretardance capabilities. Other variations may also be provided.

FIG. 6 illustrates a flow chart of a method 600 for making or using apolarization scrambler with a retardance element (RE), according to anexample. The method 600 is provided by way of example, as there may be avariety of ways to carry out the method described herein. Although themethod 600 is primarily described as being performed by the polarizationscrambler shown in configurations 100, 300, 400, and/or 500 of FIGS. 1,3, 4 , and/or 5, respectively, the method 600 may be executed orotherwise performed by one or more processing components of anothersystem or a combination of systems. Each block shown in FIG. 6 mayfurther represent one or more processes, methods, or subroutines, andone or more of the blocks may include machine readable instructionsstored on a non-transitory computer readable medium and executed by aprocessor or other type of processing circuit to perform one or moreoperations described herein.

At block 601, an optical fiber input may be provided. The optical fiberinput may transmit an optical signal. In some examples, the opticalfiber input may include an array of N×X optical fibers, where N and Xare integers, as described above.

At block 602, a beam expander may be provided. The beam expander mayreceive and expand the optical signal to create an expanded opticalsignal. In some examples, the beam expander may include a collimator, agradient-index (GRIN) lens, a bulk lens, or other beam expansionelement. In some examples, the beam expander may comprise a thin filmcoating that functions like a retardance element (RE), as describedabove.

At block 603, a retardance element (RE) may be provided. The RE maycause a polarization scrambling effect on the expanded optical signal tocreate a scrambled expanded optical signal. In some examples, theretardance element (RE) may be formed of a textured material, a polymer,a birefringent material, spatial-light-modulation (SLM) based material,or any material that has domains or regions that causes a scrambling orbirefringent effect. In some examples, the birefringent material mayinclude a liquid crystal (e.g., a birefringent organic liquid crystalpolymer (LCP), a form-birefringent inorganic dielectric thin film, or aphase controlled surface treatment, as described above. In someexamples, the RE may be a patterned retardance element (RE) having arandomized pattern, as described above. In some examples, the retardanceelement (RE) may also include a motor arm to move the retardance element(RE) in at least one of an x-, y-, or z-plane, as described above.

At block 604, a beam reducer may be provided. The beam reducer may be asimilar (but reverse in function) to the beam expander. For example, thebeam reducer may receive and reduce the scrambled expanded opticalsignal to create a scrambled optical signal.

At block 605, an optical fiber output may be provided. The optical fiberoutput may receive the scrambled optical signal. In some examples, theoptical fiber output may transmit the scrambled optical signal to one ormore downstream optical components.

It should be appreciated that the polarization scrambler may mitigatepolarization-dependent effects by using a retardance element asdescribed herein to synthesize or emulate desired state of polarization(SOP) effects. It should also be appreciated that the polarizationscrambler, as described herein, may also include or communicate withother components not shown. For example, these may include externalprocessors, counters, analyzers, computing devices, and other measuringdevices or systems. This may also include middleware (not shown) aswell. The middleware may include software hosted by one or more serversor devices. Furthermore, it should be appreciated that some of themiddleware or servers may or may not be needed to achieve functionality.Other types of servers, middleware, systems, platforms, and applicationsnot shown may also be provided at the back-end to facilitate thefeatures and functionalities of the testing and measurement system.

Moreover, single components may be provided as multiple components, andvice versa, to perform the functions and features described herein. Itshould be appreciated that the components of the system described hereinmay operate in partial or full capacity, or it may be removed entirely.It should also be appreciated that analytics and processing techniquesdescribed herein with respect to the polarization scrambler, forexample, may also be performed partially or in full by other variouscomponents of the overall system.

It should be appreciated that data stores may also be provided to theapparatuses, systems, and methods described herein, and may includevolatile and/or nonvolatile data storage that may store data andsoftware or firmware including machine-readable instructions. Thesoftware or firmware may include subroutines or applications thatperform the functions of the polarization scrambler and/or run one ormore application that utilize data from the polarization scrambler orother communicatively coupled system.

The various components, circuits, elements, components, and interfaces,may be any number of mechanical, electrical, hardware, network, orsoftware components, circuits, elements, and interfaces that serves tofacilitate communication, exchange, and analysis data between any numberof or combination of equipment, protocol layers, or applications. Forexample, the components described herein may each include a network orcommunication interface to communicate with other servers, devices,components or network elements via a network or other communicationprotocol.

Although examples are directed to a polarization scrambler for test andmeasurement systems, it should be appreciated that that polarizationscrambler may also be used in other various systems and otherimplementations. For example, the polarization scramblers and methods,as described herein, may have numerous applications in opticalcommunication networks and fiber sensor systems as well. In someexamples, a polarization scrambler may be used at the transmitter sideto minimize polarization dependent gain (PDG) or polarization holeburning of erbium-doped fiber amplifiers (EDFA) in ultra-long haulsystems. For this application, scrambling rate may be significantlyfaster than the inverse of gain recover time constant of the fiberamplifiers (e.g., on the order of 10 kHz).

The polarization scramblers and methods, as described herein, may alsobe used to assist the monitoring of polarization mode dispersion (PMD)in a wavelength-division multiplexing (WDM) system. Generally speaking,PMD may be monitored by measuring degree of polarization (DOP) of anoptical data stream propagated through an optical fiber. A small DOP mayindicate a large PMD effect. However, such a measurement may beerroneous if input SOP to a transmission fiber is substantially alignedwith a principal state of polarization (PSP) of the fiber. For such asituation, the measured DOP may be large no matter how large adifferential group delay (DGD) between the two principal states ofpolarization is. It should be appreciated that a scrambler at thetransmitter side may be used to effectively eliminate such an anomaly.Furthermore, it may enable a polarimeter in a PMD compensator at thereceiver side to identify the PSP, which in turn may speed up PMDcompensation. Other optical network applications include signal-to-noiseratio monitoring of WDM channels, e.g., if a polarizer is placed after ascrambler.

In some examples, the polarization scramblers and methods, as describedherein, may also be used to eliminate the polarization fading of a fibersensor. In such a system, an envelope of a response curve may beindependent of polarization fluctuation. Placing a polarizationscrambler, for instance, in front of a polarization sensitiveinstrument, such as diffraction grating based optical spectrum analyzer,may effectively eliminate or reduce its polarization dependence.

It should be appreciated that the polarization scramblers and methodsdescribed herein may also be used to help provide, directly orindirectly, measurements for distance, angle, rotation, speed, position,wavelength, transmissivity, and other related optical measurements. Withadvantages that include low insertion loss, low back reflection, lowresidual amplitude and phase modulation, low wavelength and temperaturesensitivity, low cost, and small form factor, the polarizationscramblers and methods described herein may be beneficial in manyoriginal equipment manufacturer (OEM) applications, where they may bereadily integrated into various and existing network equipment, fibersensor systems, test and measurement instruments, or other systems andmethods. The polarization scramblers and methods described herein mayprovide mechanical simplicity and adaptability to small or large opticalbeams. Ultimately, the systems and methods described herein may minimizebulkiness, increase control and modulation, and reduce costs.

What has been described and illustrated herein are examples of thedisclosure along with some variations. The terms, descriptions, andfigures used herein are set forth by way of illustration only and arenot meant as limitations. Many variations are possible within the scopeof the disclosure, which is intended to be defined by the followingclaims—and their equivalents—in which all terms are meant in theirbroadest reasonable sense unless otherwise indicated.

The invention claimed is:
 1. A polarization scrambler comprising: anoptical fiber input to transmit an optical signal; a beam expander toexpand the optical signal from the optical fiber input into an expandedoptical signal; a patterned retarder to receive the expanded opticalsignal from the beam expander and including a plurality of differentpatterns to cause different parts of the expanded optical signal fromthe beam expander to encounter different amounts of birefringence toproduce a polarization scrambling effect on the expanded optical signalto create a scrambled expanded optical signal; a motor arm to move thepatterned retarder in and out of an optical path of the optical signalin at least one of an x-, y-, or z-plane to improve the polarizationscrambling effect of the patterned retarder; a beam reducer to reducethe scrambled expanded optical signal from the patterned retarder into ascrambled optical signal; and an optical fiber output to transmit thescrambled optical signal from the beam reducer to a downstream opticalcomponent.
 2. The polarization scrambler of claim 1, wherein each of theoptical fiber input and the optical fiber output comprises an array ofN×X optical fibers, where N and X are integers.
 3. The polarizationscrambler of claim 1, wherein each of the beam expander and the beamreducer comprises one of a collimator, a gradient-index (GRIN) lens, ora bulk lens.
 4. The polarization scrambler of claim 1, wherein thepatterned retarder is formed from one of a textured material, a polymer,a birefringent material, or spatial-light-modulation (SLM) basedmaterial.
 5. The polarization scrambler of claim 4, wherein thebirefringent material comprises one of a liquid crystal, a dielectricthin film, or a phase controlled element.
 6. The polarization scramblerof claim 1, wherein the plurality of patterns in the patterned retarderare arranged in a randomized pattern to randomly divide the expandedoptical signal into smaller parts and cause the smaller parts of theexpanded optical signal to encounter the different amounts ofbirefringence to produce different states of polarization that resultsin the polarization scrambling effect.
 7. The polarization scrambler ofclaim 6, wherein the randomized pattern in the patterned retardercomprises one of a pixelated pattern, a radial pattern, a wave or zigzagpattern, a line or linear pattern, a checkered pattern, a texturedpattern, a scaled pattern, or a gradient pattern.
 8. The polarizationscrambler of claim 1, wherein the motor arm is to vibrate or oscillatethe patterned retarder to further improve the polarization scramblingeffect.
 9. A polarization scrambler, comprising: an optical fiber inputto transmit an optical signal; a beam expander to expand the opticalsignal from the optical fiber input into an expanded optical signal,wherein the beam expander includes a patterned retarder to create ascrambled expanded optical signal, wherein: the patterned retarderincludes a plurality of different patterns that cause different parts ofthe expanded optical signal to encounter different amounts ofbirefringence to produce a polarization scrambling effect on theexpanded optical signal that results in the scrambled expanded opticalsignal; the patterned retarder further includes a motor arm to move thepatterned retarder in and out of an optical path of the optical signalin at least one of an x-, y-, or z-plane to improve the polarizationscrambling effect of the patterned retarder; a beam reducer to reducethe scrambled expanded optical signal from the patterned retarder tocreate a scrambled optical signal; and an optical fiber output totransmit the scrambled optical signal to a downstream optical component.10. The polarization scrambler of claim 9, wherein each of the opticalfiber input and the optical fiber output comprises an array of N×Xoptical fibers, where N and X are integers.
 11. The polarizationscrambler of claim 9, wherein each of the beam expander and the beamreducer comprises one of a collimator, a gradient-index (GRIN) lens, ora bulk lens.
 12. The polarization scrambler of claim 9, wherein thepatterned retarder is formed from one of a textured material, a polymer,a birefringent material, or spatial-light-modulation (SLM) basedmaterial.
 13. The polarization scrambler of claim 12, wherein thebirefringent material comprises one of a liquid crystal, a dielectricthin film, or a phase controlled element.
 14. The polarization scramblerof claim 9, wherein the plurality of patterns in the patterned retarderare arranged in a randomized pattern to randomly divide the expandedoptical signal into smaller parts and cause the smaller parts of theexpanded optical signal to encounter the different amounts ofbirefringence to produce different states of polarization that resultsin the polarization scrambling effect.
 15. The polarization scrambler ofclaim 14, wherein the randomized pattern in the patterned retardercomprises one of a pixelated pattern, a radial pattern, a wave or zigzagpattern, a line or linear pattern, a checkered pattern, a texturedpattern, a scaled pattern, or a gradient pattern.
 16. The polarizationscrambler of claim 9, wherein the motor arm is to vibrate or oscillatethe patterned retarder to further improve the polarization scramblingeffect.
 17. A method comprising: providing an optical fiber input totransmit an optical signal; providing a beam expander to expand theoptical signal from the optical fiber input into an expanded opticalsignal; providing a patterned retarder to receive the expanded opticalsignal from the beam expander and including a plurality of differentpatterns to cause different parts of the expanded optical signal fromthe beam expander to encounter different amounts of birefringence toproduce a polarization scrambling effect on the expanded optical signalto create a scrambled expanded optical signal; providing a motor arm tomove the patterned retarder in and out of an optical path of the opticalsignal in at least one of an x-, y-, or z-plane to improve thepolarization scrambling effect of the patterned retarder; providing abeam reducer to reduce the scrambled expanded optical signal from thepatterned retarder into a scrambled optical signal; and providing anoptical fiber output to transmit the scrambled optical signal from thebeam reducer to a downstream optical component.
 18. The method of claim17, wherein the plurality of patterns in the patterned retarder arearranged in a randomized pattern to randomly divide the expanded opticalsignal into smaller parts and cause the smaller parts of the expandedoptical signal to encounter the different amounts of birefringence toproduce different states of polarization that results in thepolarization scrambling effect.
 19. The method of claim 18, wherein therandomized pattern in the patterned retarder comprises one of apixelated pattern, a radial pattern, a wave or zigzag pattern, a line orlinear pattern, a checkered pattern, a textured pattern, a scaledpattern, or a gradient pattern.
 20. The method of claim 17, wherein themotor arm is to vibrate or oscillate the patterned retarder to furtherimprove the polarization scrambling effect.